I'm using GF 1.5 RC 4.2 and Paypal Addon-beta 6. I noticed a small bug. When I set up a form that allows the user to enter any amount in a donation field a bit of jquery is activated on keyup and the amount is formated and rounded up. For example 12.399 would look like $12.40 on keyup. (which may be a nice option to enable or disable)
With a subscription where the user can enter any amount the amount stays the same. Our 12.399 would submit 12.399.
This should be an easy thing to fix just wanted to make you aware of it. I could also be missing a setting somewhere in the form but I've checked the settings a few times.